The marshlands provide a variety of habitats and subhabitats whose 

 properties change daily with tidal and seasonal conditions. Animal popula- 

 tions respond with zonations and marked fluctuations which reflect life 

 cycles, tidal exchange, and migrations to escape inundation. In this 

 study, it was impossible to fully characterize these fluctuating populations 

 over the variety of marshes and habitats studied. The approach was to 

 sample the major habitat types in the marsh ecosystem (Fig. 2), and to 

 collect comparative samples from other estuarine habitats such as tidal 

 flats and bay channels. Extensive sampling was conducted in level marshes, 

 the most widely distributed, and tidal creeks, the most likely contributors 

 to aquatic food chains of the marsh habitats. 



III. METHODS 



1 . General . 



The basic objective of this research was to characterize the inverte- 

 brate and fish life of the Siletz Bay and Netarts Bay marshes. Sampling, 

 which varied with weather and tidal conditions, was conducted at approxi^- 

 mately 2-month intervals. The greatest sampling effort was made in the 

 spring and summer. Most collections were either one-time surveys or 

 repeated surveys as opportunities arose. The only habitat for which 

 seasonal data were collected was the submerged marshes (invertebrate 

 fauna). On some occasions, two work crews were used to exploit a brief 

 sampling time frame (e.g., a single high tide). Table 3 lists the various 

 sampling devices and their uses. Appendix A provides suggestions for gear 

 improvement . 



2 . Invertebrate Studies . 



Aquatic invertebrate samples from level marsh, pan, tidal creek, and 

 adjacent tidal flat habitats were routinely processed and preserved in 

 the field using a 5- to 10-percent buffered seawater formalin solution. 

 Occasionally, it was necessary to process samples in the laboratory after 

 storage in an ice chest for a day. Such treatment had no observable 

 effect on the stored animals. Except for terrestrial and certain core 

 samples, all samples were sieved on 0.5-millimeter screens or were obtained 

 with 0.5-millimeter-mesh nets. 



After several days storage in formalin solution, the samples were 

 transferred to a 70-percent isopropanol solution and stained with rose 

 bengal or a similar stain to enhance visibility of the animals during 

 sorting. Samples were sorted, under a 3-diopter illuminated lens, to 

 broad taxonomic groups, and later identified. Usually, crustaceans, 

 polychaetes, and bivalves were identified to genus or species, insects to 

 family, and other groups to higher taxa (order, class, etc.). When appro- 

 priate, life stage {_e.g., adult, larva, pupa) was recorded. Invertebrate 

 classification follows Barnes (1974) and Borror, DeLong, and Triplehorn 

 (1976) . 



The aquatic samples varied widely in quantity of debris and number of 

 animals collected. To facilitate processing, the samples were separated 

 by stacked sieves into two size groups (0.5 to 2 millimeters and >2 milli- 

 meters) or split quantitatively with a Folsom plankton splitter. This 



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